1. Field of the Invention
The present invention relates to an automobile headlamp having a reflector with a reflecting surface over which a plurality of light distribution steps are arranged.
2. Related Art
Many conventional automobile headlamps are constructed so that the light distribution of parallel luminous fluxes are controlled with lens steps, the parallel luminous fluxes being obtained-by rays of light reflected at a reflecting surface formed of a paraboloid of revolution.
However, in many of the headlamps a large inclination angle is set for their lens to meet recent demand in automobile design, and for such headlamps there is a limitation in the light distribution control based only on the lens steps. Further, there is a demand in design that a headlamp have improved external appearance through the transparency of lens.
In order to overcome such problems, lately developed are headlamps in which all or part of the light distributing functions performed by the lens is delegated to a reflector. That is, as disclosed in U.S. Pat. No. 5,171,082, a reflector in such headlamps is characterized as having a reflecting surface over which a plurality of light distribution steps are arranged and as obtaining desired light distribution characteristics either without forming lens steps or only by forming partially shallow lens steps by forming the light distribution steps into appropriate curved surfaces. A reflector having such a reflecting surface will hereunder be referred to as a "stepped reflector".
Such a stepped reflector requires that the reflecting surface of which be divided into a number of small segments. However, it is desired that the external appearance of a headlamp be improved by minimizing the division of the reflecting surface into small segments. Further, a horizontally extending step is formed along the border between the vertically adjacent light distribution steps on the stepped reflector. In this conjunction, a consideration must be made lest upward scattering light should be generated from such horizontally extending step by appropriately designing the direction of this horizontally extending step, and this has been one of the reasons why optical designing has been a complicated operation.